I would say that you are on the right track with limiting your body parts throughout the week. I only do one body part so that I can achieve ultimate failure on my lifts. I always feel like if I could do another body part following a workout, say first chest then tri's, then I haven't burned myself out enough.
You are going for mass right? Dude, up your weights. Mass will not be built with 20 - 30 lb weights. It doesn't matter what anyone says. Get a minimum of 5 reps with the higher weight and you'll see results much faster! With that said, your protein intake and the right amount of rest is crucial!!
Good luck bro... stick with it.
You only read the first post of the topic I bet. I switched my routine to full-body now and the results are better than I had before.